Inclusive b-quark and upsilon production in DØ Horst D. Wahl Florida State University DIS 2005, Madison

Outline Tevatron and DØ detector Bottomonium ϒ(1S) production High pt μ-tagged jet production conclusion

Next to leading order Leading order Flavor excitation Flavor creation Gluon splitting

Recent developments Beyond NLO: resummation of log(pt/m) terms  FONLL Changes in extraction of fragmentation function from LEP data New PDFs Improved treatment of experimental inputs (use b-jets and b-hadrons instead of b-quarks)

Open Heavy Flavor Production Long-standing “discrepancies” between predicted and measured cross sections now resolved; e.g. Cacciari, Frixione, Mangano, Nason, Ridolfi,JHEP 0407 (2004) 033 combined effects of better calculations (Fixed order (NLO)+ NLL= FONLL) relationship/difference between e+e−and hadron colliders different moments of FF relevant better estimate of theory errors (upward!) new appreciation of issues with“quark-level” measurements Total Cross sections (from CDF): –inclusive b cross section: |y<1| 29.4±0.6±6.2 µb hep-ex/0412071 (submitted to PRD) inclusive c cross section: ~50x higherPRL 91, 241804 (2003)

B Production at the Tevatron – Finally NLO QCD and data agree 􀂄 PDF’s add more gluons 􀂄 Fragmentation measurements from LEP 􀂄 define your signal – bquark, B+, Hb 􀂄 All this can shift the same matrix element prediction by factor more than 2 !

Comments: Tevatron as HF Factory 􀂃The cross sections given on the previous slide imply central (|y|<1) b’s at 3kHz at current luminosities ~2x this if you look out to |y|<2 central charm at 150kHz –~2x1010 b’s already seen by CDF and DØ in Run II –~1x1012 charm hadrons already produced(!) ⇒ Near infinite statistics for some measurements ⇒ If you can trigger... Rely heavily on muon triggers J/ψ decays are golden semi-leptonic decays- rare decays with leptons Tracks with significant b/σb Missing neutrals troublesome forget o identification all-charged decay modes

􀂃Slightly different theoretical context– Quarkonia Production 􀂃Slightly different theoretical context– Non-relativistic QCD (NRQCD) Lepage et al., PRD 464052 (1992) Production described by short distance cross sections ⊕ non-perturbative matrix elements for evolution to quarkonium state. color octet modes required on top of color singlet to describe production (demonstrated by CDF in Run I) New results from DØ: (1s) production, →µµ final state submitted to PRL: hep-ex/0502030

Solenoid, Tracking System (CFT, SMT) The DØ Detector Muon Toroid Calorimeter Just as a reminder: We are the ones with the good muon system and the new tracker. Solenoid, Tracking System (CFT, SMT)

DØ tracking system Silicon Tracker Fiber Tracker Solenoid 125 cm h=1.6 h=3 50cm 20cm Forward Preshower detector Solenoid Central Preshower detector

DØ - Muon detectors Toroid magnet (1.9 T central, 2.0 T forward) Scintillation counters PDTs (central) MDTs (forward) A-f Scint Forward Tracker (MDTs) Shielding Bottom B/C Scint PDT’s Forward Trigger Scint

The DØ Trigger System The DØ Trigger System Towers, Tracks, missing ET Some correl’s Single Sub-Det’s Not quite deadtimeless Correlations Calibrated Data Physics Objects e,,jets,,missing ET Simple Reco Physics Algorithms L3 L1 L2 1 kHz 50 Hz 2 kHz Decision time ~50ms 1.7 MHz Decision time 100ms Decision time 4.2ms L1 Missing L1 Fiber Tracker Trigger - expected by end of summer Essential for low pT central muon trigger L2 Current rates: L1/L2/L3 ~ 1600/900/50 Hz

Bottomonium production Theory modeling of production Quarkonium production is window on boundary region between perturbative and non-perturbative QCD factorized QCD calculations to O(α3) (currently employed by Pythia) color-singlet, color-evaporation, color-octet models Recent calculations by Berger et al. combining separate perturbative approaches for low and high-pt regions Predict shape of pt distribution Absolute cross section not predicted ϒ(1S) Production @ Tevatron: 50% produced promptly, i.e. at primary vertex 50% from decay of higher mass states (e.g. χb →ϒ(1S) ) Event selection - luminosity: 159.1 ± 10.3 pb-1 - di-muon: pT>3, tight Tracking and Calorimeter isolation cut - invariant mass in 7 – 13 GeV

LO/NLO/NNLO QCD including flavor excitation gluon splitting b-quark production LO/NLO/NNLO QCD including flavor excitation gluon splitting each process results in different correlations between the two b-quarks. the plots for the first points only shows LO, NLO are loop diagrams gluon splitting (= fragmentation?) will have almost parallel b-mesons LO will have b-mesons back to back

b-tagging at DØ Offline trigger level ptrel impact parameter Secondary vertex trigger level Silicon Track Trigger (STT) at Level 2 impact parameter at Level 3

Tagging b-jets: μ local muons only

Tagging b-jets: impact parameter track jet axis jet axis dca track Jet axis from primary vertex + calorimeter. primary vtx positive IP negative IP

Tagging Tools: Vertexing and Soft Muons B hadrons in top signal events Vertex of displaced tracks Identify low-pt muon from decay

Why measure ϒ(1S) production at DØ Because we can: The ϒ(1S) cross-section had been measured at the Tevatron (Run I measurement by CDF) up to a rapidity of 0.4. DØ has now measured this cross-section up to a rapidity of 1.8 at √s = 1.96 TeV Measuring the ϒ(1S) production cross-section provides an ideal testing ground for our understanding of the production mechanisms of heavy quarks. There is considerable interest from theorists in these kinds of measurements: E.L. Berger, J.Qiu, Y.Wang, Phys Rev D 71 034007 (2005) and hep-ph/0411026; V.A. Khoze , A.D. Martin, M.G. Ryskin, W.J. Stirling, hep-ph/0410020

The Analysis Goal: Measuring the ϒ(1S) cross-section in the channel ϒ(1S) → μ+μ- as a function of pt in three rapidity ranges: 0 < | yϒ| < 0.6, 0.6 < | yϒ | < 1.2 and 1.2 < | yϒ | < 1.8 Sample selection Opposite sign muons Muon have hits in all three layers of the muon system Muons are matched to a track in the central tracking system pt (μ) > 3 GeV and |η (μ)| < 2.2 At least one isolated μ Track from central tracking system must have at least one hit in the Silicon Tracker

Efficiencies,… Cross section: = N(¡) d2σ(¡(1S)) dpt × dy L × Δpt × Δy × εacc× εtrig× kdimu× ktrk× kqual = L Luminosity kdimu local muon reconstruction y rapidity ktrk tracking εacc Acceptance kqual track quality cuts εtrig Trigger 0.0 < y < 0.6 0.6 < y < 1.2 1.2 < y < 1.8 εacc 0.15 - 0.26 0.19 – 0.28 0.20 - 0.27 εtrig 0.70 0.73 0.82 kdimu 0.85 0.88 0.95 ktrk 0.99 0.99 0.95 kqual 0.85 0.85 0.93

MC Data* Data vs Monte Carlo . η(μ) φ(μ) pt(μ) in GeV To determine our efficiencies, we only need an agreement between Monte Carlo and data within a given pT(ϒ) and y(ϒ) bin and not an agreement over the whole pT(ϒ) and y(ϒ) range at once . MC Data* η(μ) φ(μ) pt(μ) in GeV 0 5 10 15 20 -2 -1 0 1 2 0 3 6 *9.0 GeV < m(μμ) < 9.8 GeV 0.6 < | yϒ| < 1.2

Fitting the signal Signal: 3 Gaussians: ¡(1S), ¡(2S), ¡(3S) Fitting a single Gaussian recovers ~95 % of the signal. Background: 3rd order polynomial m(¡(2/3S)) = m(¡(1S)) + ∆ mPDG(¡(2/3S)-¡(1S)) σ(¡(2/3S)) = m(¡(2/3S)/m(¡(1S)) * σ(¡(1S)) →5 free parameters in signal fit: m(¡(1S)), σ(¡(1S)), c(¡(1S)), c(¡(2S)), c(¡(3S)) All plots: 4 GeV < pt(¡) < 6 GeV PDG: m(¡(1S)) = 9.460 GeV m(¡) = 9.419 ± 0.007 GeV m(¡) = 9.412 ± 0.009 GeV m(¡) = 9.437 ± 0.010 GeV 0 < |y¡ | < 0.6 0.6 < |y¡ | < 1.2 1.2 < |y¡ | < 1.8

Questions: a) Why do we parametrize the signal as two Gaussians ? b) How do we determine the shape of these two Gaussians ? J/ψ → µµ single Gauss double Gauss

Question: Why do we use different fitting ranges for different bins ? The fit assumes a smooth background. We choose the fitting range accordingly. ptϒ 1-2 GeV yϒ 1.2 - 1.8 With increasing ptϒ the mass peaks widens, but background is better behaved → increased fitting range We derive a systematic error from varying our fitting range.

Fitting - Results ● The fitted width is pt independent ● The resolution is ~30% worse than in MC ● The (relative) widening of the peak in the forward region is reproduced by MC Width ϒ(1S) 0 0.25 0.5

Fitting - results Ratio of n((2S+3S))/n((1S)

Normalized differential cross section very little difference in shape of the distribution as a function of the ϒ rapidity Good agreement with calculation of Berger, Qiu, Wang

Results: dσ(ϒ(1S))/dy × B(ϒ(1S) → µ+µ-) 0.0 < yϒ < 0.6 732 ± 19 (stat) ± 73 (syst) ± 48 (lum) pb 0.6 < yϒ < 1.2 762 ± 20 (stat) ± 76 (syst) ± 50 (lum) pb 1.2 < yϒ < 1.8 600 ± 19 (stat) ± 56 (syst) ± 39 (lum) pb 0.0 < yϒ < 1.8 695 ± 14 (stat) ± 68 (syst) ± 45 (lum) pb CDF Run I: 0.0 < yϒ < 0.4 680 ± 15 (stat) ± 18 (syst) ± 26 (lum) pb

Comparison with previous results σ(1.2 < yϒ < 1.8)/σ(0.0 < yϒ < 0.6) Pythia

Questions: Why does the mass peak widen in the forward region ? How is the increased resulting smearing corrected in the cross section ? The tracking resolution is worse in the forward region, as the tracks have a higher momentum and intersect with the tracking detectors at an angle. This trend is reproduced in our Monte Carlo. We increase the Monte carlo resolution by 30% over the default to match what we see in data. The momentum scale is corrected for using the difference between measured and PDG ϒ(1S) mass. Question: Does the mass resolution really scale with the mass of the particle ? Yes. Both in data (compared to J/ψ →µµ) and in Monte-Carlo.

Questions: Do we understand the rapidity dependence of our correction factors k_qual and k_trk ? Track quality cuts: At least 1 SMT hit on each track. At least one of the tracks forming an ϒ has to be isolated. k_trk (Tracking efficiency): The Monte-Carlo overestimates the tracking efficiency in the forward region as it does not take the faulty SMT disks into account. k_qual: SMT hit requirement: If we do find a track in the forward region in data, it will have an SMT hit, as there is nothing else to make a track. Therefore the SMT hit requirement affects the forward region less than the central region. Isolation: In MC the isolation requirement is 100% efficient, i.e. we do not loose any signal when applying it. In data we loose up to 6% of the signal, but considerably less in the forward region.

Question: What is the L1 trigger efficiency per muon ? We only determine the trigger efficiency for dimuons. Approximately half the muons from ϒ(1S) have a pt < 5 GeV. Trigger turn-on curve from Rob McCroskey µ from ϒ(1S) log scale 0 3 5 9 GeV

Effects of polarization CDF measured ϒ(1S) polarization for |yϒ| < 0.4. How can we be sure that our forward ϒ(1S) are not significantly polarized ? So far there is no indication for ϒ(1S) polarization. CDF measured α = -0.12 ± 0.22 for pT (ϒ)> 8 GeV α = 1 (-1) ⇔ 100% transverse (longitudinal) polarization The vast majority of our ϒ(1S) has pT(ϒ) < 8 GeV Theory predicts that if there is polarization it will be at large pT. No evidence for polarization in our signal (|y| < 1.8); ---- not enough data for a fit in the forward region alone. estimated the effect of ϒ(1S) polarization on our cross-section: Even at α = ± 0.3 the cross-section changes by 15% or less in all pT bins. same effect in all rapidity regions.

Question: Why is CDF's systematic error so much smaller than ours ? Better tracking resolution --- CDF can separate the three ϒ resonances: → Variations in the fit contribute considerable both to our statistical and systematic error. → We believe we have achieved the best resolution currently feasible without killing the signal Poor understanding of our Monte-Carlo and the resulting large number of correction factors. Signal is right on the trigger turn-on curve.

Conclusions ϒ(1S) cross-section μ-tagged jet cross section: Presented measurement of ϒ(1S) cross section • BR(→μμ) for 3 different rapidity bins out to y(ϒ) = 1.8, as a function of pt(ϒ) First measurement of ϒ(1S) cross-section at √s = 1.96 TeV. Shapes of dσ/dpt show very little dependence on rapidity. Normalized dσ/dpt is in good agreement with published results (CDF at 1.8TeV) μ-tagged jet cross section: Measured dσ/dpt in central rapidity region |y|<0.5 for μ-tagged jets originating from heavy flavor

Backup slides

Where do the ϒ(1S) come from ? ~ 50 % of ϒ(1S) are produced directly. The rest are the result of higher mass states decaying. Bottomonium States

Fitting the signal Fitting a single Gaussian recovers ~95 % of the Signal: 3 Gaussians: ¡(1S), ¡(2S), ¡(3S) Background: 3rd order polynomial m(¡(2/3S)) = m(¡(1S)) + mPDG(¡(2/3S)-¡(1S)) σ (¡(2/3S)) = m(¡(2/3S)/m(¡(1S)) * σ σ (¡(1S)) →5 free parameters in signal fit: m(¡(1S)), σ(¡(1S)), c(¡(1S)), c(¡(2S)), c(¡(3S)) All plots: 3 GeV < pt(¡) < 4 GeV PDG: m(¡(1S)) = 9.46 GeV m(¡) = 9.423 ± 0.008 GeV m(¡) = 9.415± 0.009 GeV m(¡) = 9.403 ± 0.013 GeV 7 8 9 10 11 12 13 7 8 9 10 11 12 13 7 8 9 10 11 12 13 GeV GeV GeV 0 < |y¡ | < 0.6 0.6 < |y¡ | < 1.2 1.2 < |y¡ | < 1.8

Fitting the Signal PDG: m(¡(1S)) = 9.46 GeV 1.2 < |y¡ | < 1.8 Signal: 3 states (ϒ(1S), ϒ(2S), ϒ(3S)), described by Gaussians with masses mi, widths (resolution) σi, weights ci ,(i=1,2,3) Masses mi= m1+ m i1(PDG), widths σi = σ1 •(mi/m1), for i=2,3 free parameters in signal fit: m1, σ1, c1, c2, c3 Background: 3rd order polynomial PDG: m(¡(1S)) = 9.46 GeV m(¡) = 9.415± 0.009 GeV m(¡) = 9.403 ± 0.013 GeV m(¡) = 9.423 ± 0.008 GeV 1.2 < |y¡ | < 1.8 0.6 < |y¡ | < 1.2 0 < |y¡ | < 0.6 All plots: 3 GeV < pt(¡) < 4 GeV

Width from fit for ϒ (1S) with |yϒ| < 0.6 Data MC Width (GeV) 0.25 0.15 0.1 pt (GeV) ~ 43000 ¡(1S) candidates

Trigger Level 1: di-muon trigger, scintillator only Level 2: one medium muon (early runs) two muons, at least one medium, separated in eta and phi (later runs) Both triggers at Level 2 are ~ 97 % efficient wrt Level 1 condition. Trigger efficiency for fully reconstructed di-muon events: central region: 65 % forward region: 80 % Trigger efficiency |y(¡)| < 0.6 Data wrt single μ 0.75 MC 0.65 0 4 8 12 16 20 GeV [pt(¡)]

Corrections: Local muon reconstruction efficiency reconstruct J/ψ: muon & muon and muon & track ε = muon & muon / muon & track εData εMC |η| central muon detector forward muon detector

Corrections: Tracking efficiency Method: Reconstruct J/ψ using global (i.e. muons matched to a track in the central tracking system) and local (i.e. muons that are only reconstructed in the muon system and not matched to a central track) muons. global-local* (signal events only) global-local* (all events) global-local* (local mu only) 4000 5000 350 1 2 3 4 5 6 1 2 3 4 5 6 1 2 3 4 5 6 GeV GeV GeV * i.e. the local momentum of the test muon is used, whether is was matched or not.

Corrections: Tracking Efficiency NJ/ψ(global & global) NJ/ψ(global & local) + NJ/ψ(global & global) Efficiency = 1.0 0.8 |η| 0.0 0.4 0.8 1.2 1.6 2 2.2

Corrections: Isolation and Silicon Hit Requirement From data – Monte Carlo predicts isolation requirement to be 100% efficient. Isolation efficiency for signal | y(¡)| < 1.8 pt in GeV

Motivation Fact: The multi-generational structure of the quark doublets requires explanation and could herald compositeness. Under hypothesis of compositeness, deviation from point-like behavior would likely manifest in third generation. Conclusion: g  bb may exhibit desired deviant behavior. Explore b quark dijet mass as a possible signature. Problem ~100:1 QCD:bb Solutions m tagging 2nd VTX tagging Impact parameter CDF: PRL 82 (1999) 2038 Fit to CDF qQCD calculation

m-tagged Jet Cross-section eT Trigger Eff ePV Primary Vertex Eff ej Jet Eff em m Eff fbm Frac b  m (Pt > 4 GeV) fBm Frac B  m (Pt > 4 GeV) L Luminosity Dpt Pt bin width sHF HF cross-section sbg background cross-section Correlated Jet + m (Pt > 5 GeV) Given the simplicity of the calculation, there are few likely sources of the excess seen in p13. These could conceivably be N m JES (central value) Resolution (i.e. smearing) p13

p14 Analysis Summary Inclusive m-tagged jet corrJCCB (0.5 cone jets) Standard Jet quality cuts, Standard JET Triggers Jet tagged with MEDIUM muon (more on this later) DR(m, jet) < 0.5 |yjet| < 0.5 JES 5.3 Long term goal was b-jet xsec. Difficult due to no data-driven determination of b-fraction.

p14 Skimming Start with CSG QCD skim Turn into TMBTrees (40M events…on disk) Skim on Trees Remove bad runs (CAL, MET, SMT, CFT, JET, Muon) Remove events w/o 2 jets Use Ariel d0root_ based package SKIM 1:  1 leading jet has ~ MEDIUM m (P(m) > 4 GeV) SKIM 2:  1 leading jet has ~ loose SVT

p14 All Data: CSG Skims Bad runs & lumblk removed in luminosity. Only bad run removed in event counts for skims. Up until Run 193780 (07-JUN), V12.37.

Trigger Turn On Jet Trigger Collinear muon |yjet| < 0.5 Luminosity weighted Statistics uncorrelated poisson (wrong, of course) JES corrected (5.3)

What is now a muon? m A layer cal Medium muon (as defined by mID group) At least one scintillator hit in BC. Pt(central track) > 5 GeV |Pt(central) – Pt(global)| < 15 GeV Rejected if 4.25 < f (muon) < 5.15 AND |h(detector)| < 1.1 m A layer cal jet Fake m from punch-through In a jet environment is an issue

f Distribution of MEDIUM m-tagged jets (+ mycuts) f(jet+m) These cuts clearly improve the fake m rate. Some residual fake m’s must persist. How many? CHF should be higher for punch through jets?

Closer Look Suspicious JT45_TT Pt(m) 4.5-5.0 4.0-4.5 Pt(m)

Pt(m) Pt(m) Closer Look Suspicious JT45_TT 4.5-5.0 4.0-4.5 Applied 10% inefficiency

MEDIUM m Definition |nseg|=3 muons are muons with a A and a BC segments matched or not with a central track. A |nseg=3| muon is medium if it has: at least two A layer wire hits a A layer scintillator hit at least two BC layer wire hits at least one BC scintillator hit (except for central muons with less than four BC wire hits). A |nseg=2| muon is medium if it has: at least one BC scintillator hit at least two BC layer wire hits. (octant 5 and 6 with |detector eta|<1.6). A |nseg=1| muon is medium if it has: a A scintillator hit at least two A layer wire hits.

What is now a muon? m A layer cal Medium muon (as defined by mID group) At least one scintillator hit in BC. Pt(central track) > 5 GeV |Pt(central) – Pt(global)| < 15 GeV Rejected if 4.25 < f (muon) < 5.15 AND |h(detector)| < 1.1 m A layer cal jet Fake m from punch-through In a jet environment is an issue

PUNCHLINE: Remove the 10% inefficiency. It’s probably residual punchthrough.

Efficiencies…. Efficiency Detail Value 1.000 0.84 ± 0.005 0.37 ± 0.05 Trigger Eff 1.000 ePV Primary Vertex: |z| < 50cm, ≥ 5tracks 0.84 ± 0.005 em m Eff (geom, μ det., tracking, match) 0.37 ± 0.05 ej Jet Eff (jet quality cuts) 0.99 ± 0.01 fbgm Frac background  m (Pt > 4 GeV) Pt dependent fHFm Frac heavy flavor  m (Pt > 4 GeV) [0.37 ± 0.05]

m JES Definitions Required identically 2 jets Pt(jet 3, uncor) < 8 OR third jet doesn’t pass jet QC One jet contains muon, the other doesn’t. | Df | > 2.84 Imbalance variable: Independent variable:

Jet energy scale for μ-tagged jets μ-tagged jets also have neutrinos ⇒ offset -- correction needed Imbalance in events with 2 jets (one with, one without μ) – find 3.8% offset, not strongly pt dependent for pt in (75, 250GeV) Scale energies of μ-tagged jets by factor 1.038 Order-randomized imbalance used to get resolution STD JES 5.3 gives a 3.8% offset for m-tagged jets. It is independent of Pt (75-250 GeV). Maybe higher above that. Need to rebin and revisit the idea that the muon Pt may be mis-measured. Same plot when scaling the m-tagged jet energies by 3.8%.

Energy Resolution

resolution Neutrinos in μ-tagged jet  resolution worse than for jets without μ take rms of order randomized imbalance Parameterize, Fit (fig. (a)) Subtract (in quadrature) resolution for jets without μ  obtain resolution for μ-tagged jets (fig. (b) Fit: N = 7.7  4.1 S = 1.9  0.1 C = 0.0  0.1 Resolution parameterization used in “unsmearing”

Fitting Functions Variable Value Error N 9.56 × 107 1.7 × 106 a 3.195 0.004 b 5.61 0.04 Variable Value Error N1 7.62 0.32 k1 16.90 1.26 N2 3.28 0.60 k2 36.33 3.23

Extraction of Correction Factors “normal” exponential

Point by Point Unsmearing Factors “normal” Exponential Unsmearing Error small ~5% for Pt > 100 GeV

PtRel at High Pt PtRel muon jet

HF fraction of μ-tagged jet sample Sample of jets with μ-tagged jets contains jets with μ from non-HF sources (e.g. , K decays…) Use Pythia with standard DØ detector simulation to find HF fraction of jets tagged with muons vs (true) pt Fit with A + B e-Pt/C A = “plateau”, B = “zero” C = “turnon”

Systematic Error Breakdown

MC Comparison

Pythia using standard DØ MC. NLO uses NLO++ (CTEQ6L) From Pythia, find fraction of jets tagged with muons (HF only). Multiply NLO cross-section by Pythia muon-fraction. This is effectively the NLO k factor.

Conc DØ Note and Conference note to EB025 Residual small bug in code (should have only a few percent effect). JES error must be reduced to use this before setting limits on new physics.

- good tracking, vertex, impact parameter measuring performance - Silicon Microvertex Tracker (SMT) + Central Fiber Tracker (CFT) + 2T Solenoid - good tracking, vertex, impact parameter measuring performance Pseudo rapidity: h = -ln(tg(q/2)) Spatial separation: △R2=△f2+△h2

Muon system: - 3 layer, 1 layer (A) in 1.8T Toroid - Good coverage: central |h|<1 forward 1<|h|<2 - Muon-Tracking match  muon candidate - fast and efficient Di-Muon Trigger

U’s |y|  U‘s PT  Data sample partition: Sample fit: - Dy1: 0 ＜ |yU| ＜ 0.6 - Dy2: 0.6 ＜ |yU| ＜ 1.2 - Dy3: 1.2 ＜ |yU| ＜ 1.8 Sample fit: - Background: 3rd order polynomial - U(1,2,3S) resonances: double Gaussian - the mass and width of U(1S) are free parameters; others are fixed relative to the mass

Evaluating the U(1S) Production Xsec: with eff in different rapidity region: The measured cross-section×BR(U(1S)mm) is as

- No strong dependence on rapidity observed 749±20±75 781±21±78 598±19±56 with 6% luminosity uncertainty

Run2 preliminary results consistent with CDF Run1

measurements of U production at D0 to 1.8 rapidity region Summary: measurements of U production at D0 to 1.8 rapidity region The pT spectrum does not show significant difference in various rapidity region Results consistent with CDF RunI’s - CDF √s=1.8TeV, |y|<0.4, ds/dy*Br =680±15±18±26 pb - D0 √s=1.96TeV, |y|<0.6, ds/dy*Br =749±20±75±49 pb - PYTHIA predict a factor of 1.11 from 1.8 to 1.96 TeV